Expansible tire-vulcanizing core



A. B. MERRILL.

EXPANSIBLE TIRE VULCANIZING CORE.

APPLlcAI'loN FILED Nov. 7, 1921.

315435.97@ f -PaentedNown 21,1922.

55/ v .my

Patented Nov. 2l, N22..

- NETE@ STATES A maaar@ Parana? oberen.

ALLAN BVMEBIRILL, OIF AKRON, OHIO. ASSIGNOR TO THE B. F. GOODRICH COMPANY,

OF NEW YORK, N. Y., A CORPORATION OF NEW YORK. u

EXPANSIBLE 'rIRE-VULCANXZING conn.

Application led November 7, 1921.. Serial No. 513,319.

T o all 207mm it may concern.'

Be it known that I, ALLAN B. MERRILL, a citizen of the nited States, residing at Akron, in the county of Summit and State of Ohio, have invented a certain new and useful Expansible rl`ire-`Vulcanizing Core, of which the following is a specification.

rlfhis invention relates toannular expansible cores such. for example, as'are used in fvulcanizing pneumatic cord-tires and commonly referred to as air bags or water bags. My object is to increase the life of these bags b vdelaying the migration of an excess of sulphur into the walls of the bag from the tires being vulcanized. which eventually hardens these walls and causes the bag to crack.

The accompanying drawing is a sectional, perspective view of a water bag embodying a )referred form of my invention.

eferring to the drawing. 10 designates the bag as a whole, of which the main body 1-1 is a thick-walled, annular tube of vulcanized soft rubber having at its inner periphery a bead-engaging base portion 12 of vulcanized rubber reenforced with strips of fabric 13. The outer surface of the tube 11, except at the reenfrced base 12, is covered with a layer of rubber initially containing very little or no sulphur, commonly referred to as a.v non-vulcanizing compound. This outer layer may either be a veneer of sheeted gum 1-1 or acoating of rubber cement painted v on the bagand allowed to dry, or both. Finely-divided mica, Vindicated in the drawing by stippling, is preferably applied to the surface of the layer 14 to prevent the latter kfrom sticking to the inner surface of theetire. 15y is a valve stem such as is used in inner tubes for pneumatic tires, for supplying fluid under pressureto the interiorof the' bag.

ln use, the layer 14 absorbs the sulphur emanating from the tire body and prevents it from reaching the main body 11 of the bag and overcuring the latter. As the outer layer initially contains butga` very small quantity of sulphur, if any. it is capable of absorbing such sulphur as is given 0H to it by the tire body in a large number -of vulcanizing heats before it becomes overcured. The bag, nevertheless, withstands handling and retains its shape by reason ofthe vulcanized condition jof the thick-walled bodyportion 11 and the base 12.

rIhe bag may be made in any lmown or suitable manner, as by first forming the thick-walled tube 11 of a vulcanizable compound on a straight mandrel, removing it from the mandrel and applying the valve stem 15 thereto. joining the ends of the tube to form an annulus, intlating it, applying the base portion 1Q thereto, stretching onto said annulus the non-curing sheet of gum 11 and stitching the latter in place. subjecting the entire structure to vulcanizing heat in a mold while subjecting it to internal fiuid pressure` painting the surface of the molded bag with a thin rubber cement containing finely-divided mica. and permitting said cement to dry. l do not limit myself, however, to this or any other method of constructing the bag. nor'do l wholly limit myself to the use of mica or to the use of cement as a vehicle for applying a non-adhesive substance.

I may use a small amount of sulphur,l preferably less than 2%, in the veneer 14, with or without a filler or an accelerator, for the purpose of stilfening it, since the degree of vulcanization" which results therefrom in said veneer is comparatively small and the veneer is still capable of absorbing al substantial quantity of sulphur and withstanding many successive heats before it becomes overcured.

ln practice l nd it advisable to apply a new coat of the mixture of mica and cementV before each cure, as a safeguard against sticking of the bag to the tire and to retard A to some extent the migration of sulphur.

`When the outer surface of the veneer 14 eventually becomes overcured and begins to crack, a part or all of it may be bued off and replaced by a new layer of the substantially sulphur-free compound, and as t-he body portion 11 contains little if any more sulphur than it did originally the bag againk may be used for a large number of cures. This process of renewing the bagis not a part of my invention, but after suc-h renewal, as well l'as before, the bag itselfy embodies my invention.

My invention is subject to modifications and r do not limit my claims wholly to the form herein described.

'll claim: y

1. An expa-nsible core for vulcanizing rubber' articles, said core comprising a wall of vulcanized rubber and a surface laye-r of relatively non-vulcanizing material thereon adapted to prevent migration of sulphur to said Wall from the article being vulcanized.

2. Aniexpansible core for vulcanizing rubber articles, said core comprising a Walli'of vulcanized rubber, and a' layer of'sulphurabsorbing materialthereon, said layer eX- tending substantially to the Work contacting surface of said core. v

3. An eXpansible core for vulcanizing rubber articles, said core comprising layers of rubber of different sulphur content, the

outermost layer of-"rubber 1n said core initially containing less than v2% of sulphur.

4. An expansible core'vfor vulcanizing rubber articles, said core comprising'a Wall of vulcanized rubber and a layer of substantially sulphur-free rubber thereon, said layer constituting the Ioutermost layer of rubberfin said core. v

'5. An expansible core .for vulcanizing rubber articles, said core comprising a rubber Wall initially containing a smaller proportion of sulphur at the face thereof than in a region relatively .remote therefrom.

6. 'An expansible core `for vulcanizing rubber articles,l said core comprising a -stretchable Wall, a layer of substantially sulphurfree rubber thereon, Asaid layer constituting the outermost layer of rubber in said core,

and material associated with said g layer adapted'to prevent the latter from sticking to the work.

7. An expansible core forvulcanizing rubber'articles, said core comprising a lstretchable Wall, a layer of substantially sulphurfree rubber thereon, 'said layer constituting the outermost ,layer of rubberinsaidcore, and nely-divided mica uponsaid layer.

8. Apparatus for vulcanizing pneumatic tires comprising an annular ltube of vulcan' ized rubber, a coating ofsubstantially sulphur-free rubber compound thereon, Isaid layer constituting the" outermost layer-v of rubber in said core, and means for preventing said coating from adhering to the surface of the tire when the latter is vul; canized in Contact with said coating.

my hand this 3d day of Novembe1, 1921.[

. ALLAN B. MERRILL.

In Witness whereof` I have hereunto `set r 

